1. Field of the Invention
The present invention relates to a fixing apparatus mounted in an image forming apparatus such as a copier, a printer or a facsimile, and particularly to a fixing apparatus of an image forming apparatus, which uses an induction heating system.
2. Description of the Background
Among induction heating fixing apparatuses used in image forming apparatuses such as electrophotographic copiers or printers, there is an apparatus which prevents a part of a fixing member from being excessively heated. For example, JP-A-2005-321511 discloses a fixing apparatus in which separation between a first fixing member and a second fixing member is detected, and power supply to a heat generating part is cut off. Besides, for example, JP-A-2002-82549 discloses a fixing apparatus in which after a heat generating roller in contact with a fixing belt starts a rotation operation, the heat generating roller is excited to generate heat.
However, as in the related art fixing apparatus, when the temperature control of the heat generating part is performed only by the timing of contact and separation of the fixing member, in the case where the fixing member having a small heat capacity is used, when the fixing members at the heating side and the pressure side come in contact with each other, a temperature drop in the fixing member becomes large. Thus, there is a fear that defective quality of fixing image occurs at the time of first copying.
Thus, in the induction heating fixing apparatus, it is desired that a fixing apparatus of an image forming apparatus is developed in which defective quality of fixing image due to a temperature drop in a heat generating member caused at the time of contact with an opposite member is prevented and a stable fixing property is obtained.